New report calls for early warning system regarding abrupt climate change events

A new National Research Council report calls for the development of an early warning system that could help society better anticipate sudden changes resulting from climate change and their impacts on society, says a University of Colorado Boulder faculty member who chaired the committee that produced the report.

Climate change has increased concern over possible large and rapid changes in the physical climate system, including Earth’s atmosphere, land surfaces and oceans, said Professor James White of CU-Boulder’s Institute of Arctic and Alpine Research and the chair of the National Research Council committee. Some abrupt changes and impacts already underway – including the loss of Arctic sea ice and increases in the extinction rates of marine and terrestrial species – and others could occur within a few decades or even years, said the committee.

“Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century,” said White, also a CU-Boulder professor in geological sciences. “Evaluating climate changes and impacts in terms of their potential magnitude and the likelihood they will occur will help policymakers and communities make informed decisions about how to prepare for or adapt to them.”

Other scenarios, such as the destabilization of the west Antarctic ice sheet, have potentially major consequences, but the probability of these changes occurring within the next century is not well understood, highlighting the need for more research, according to the committee.

In some cases, scientific understanding has progressed enough to determine whether certain high-impact climate changes are likely to happen within the next century. The report notes that a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice are now known to be unlikely this century, although these potential abrupt changes are still worrisome over longer time horizons.

But even changes in the physical climate system that happen gradually over many decades or centuries can cause abrupt ecological or socio-economic change once a "tipping point" is reached, the report adds. Relatively slow global sea-level rise could directly affect local infrastructure such as roads, airports, pipelines or subway systems if a sea wall or levee is breached. And slight increases in ocean acidity or surface temperatures could cross thresholds beyond which many species cannot survive, leading to rapid and irreversible changes in ecosystems that contribute to extinction events.

Further scientific research and enhanced monitoring of the climate, ecosystems and social systems may be able to provide information that a tipping point is imminent, allowing time for adaptation or possibly mitigation, or that a tipping point has recently occurred, the report says.

“Right now we don’t know what many of these thresholds are,” White said. “But with better information, we will be able to anticipate some major changes before they occur and help reduce the potential consequences.” The report identifies several research needs, such as identifying keystone species whose population decline due to an abrupt change would have cascading effects on ecosystems and ultimately on human provisions such as food supply.

If society hopes to anticipate tipping points in natural and human systems, an early warning system for abrupt changes needs to be developed, the report says. An effective system would need to include careful and vigilant monitoring, taking advantage of existing land and satellite systems and modifying them if necessary, or designing and implementing new systems when feasible. It would also need to be flexible and adaptive, regularly conducting and alternating between data collection, model testing and model predictions that suggest future data needs.

The study was sponsored by the National Oceanic and Atmospheric Administration, National Science Foundation, U.S. intelligence community, and the National Academies. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, independent nonprofit institutions that provide science, technology, and health policy advice under a congressional charter granted to NAS in 1863. The National Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering.